<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        *{
            margin: 0;
            padding: 0;
        }
        .container{
            width: 750px;
            margin: 0 auto;
        }
        .container ul li{
            list-style: none;
            float: left;
            width: 93.75px;
            height: 30px;
            background-color: green;
            color: white;
            text-align: center;
        }

        @media screen and (max-width: 767px){
            .container{
                width: 100%;
            }

            .container ul li{
                width: 33.33%;
            }
        }
    </style>
</head>
<body>
    <div class="container">
        <ul>
            <li>导航栏</li>
            <li>导航栏</li>
            <li>导航栏</li>
            <li>导航栏</li>
            <li>导航栏</li>
            <li>导航栏</li>
            <li>导航栏</li>
            <li>导航栏</li>
        </ul>
    </div>
</body>
</html>